road bleeds into all road bleeds into gravel bleeds into MTB.
modern (bro) wisdom would say you need to clear 50C to get a really capable gravel bike (as per Dylan Johnson on YT, basically).
If you want to do chunky gravel, then that's probably what you want. 30/32C Conti GP5000 tyres on a road wheelset, and 50C tyres on a gravel one. Or potentially 650b wheels with big mountain bike tyres (see Dylan Johnson's recent bike setup videos for gravel races).
If you aren't going to do any "real gravel" / chunky stuff, potentially an all road bike that takes 38C may be enough, at which point you might get away running 1 wheelset only.
really does depend on the riding you are ACTUALLY going to be doing.
I only have good things to say about carbonspeed's Grevil clone & Peter himself (Peter is on the forum.
http://www.xmcarbonspeed.com/Productinfo.asp?f=1639). My er9 died on it after 4 rides, but i really enjoyed it. it's very roadie, in the sense that you can go really fast on it on smooth roads. It's the same geometry exactly as the Grevil, and Pinarello do know a thing or 2 about bike geometry apparently. it takes 50C.
I can also say good things about Long teng, and their newer model takes 38C (
https://www.ltbikes.com/index/products/view/id/401.html). I have the 268, and the geometry is very similar, so it's a road bike, but "all road".
I also have a VB GF02 but honestly as a road bike it's pretty awful. i bought that, then very quickly decided to buy a real road bike, hence the LT. The Grevil clone would likely be capable of both quite well. 90+% of the riding i want to do is road, i bought gravel bikes to basically realize i like road better... but that's very much a function of where you live. the US has such poor infrastructure that a lot of roads are white roads. Europe doesnt have that, unless you're in the ass of somewhere, there's asphalt.
Pro tip: if 99% of your riding is going to be road, buy a road bike
